WO2004004014A1

WO2004004014A1 - Semiconductor device and its manufacturing method

Info

Publication number: WO2004004014A1
Application number: PCT/JP2003/007761
Authority: WO
Inventors: Heiji Watanabe; Kazuhiko Endo; Kenzo Manabe
Original assignee: Nec Corporation
Priority date: 2002-06-27
Filing date: 2003-06-19
Publication date: 2004-01-08
Also published as: CN1663051A; AU2003244275A1; US8125016B2; US20120181632A1; CN100367513C; JP2004031760A; US8575677B2; US20050247985A1; JP4643884B2

Abstract

A semiconductor device having a gate insulting film and a gate electrode formed in this order on a silicon substrate, wherein the gate insulating film includes a nitrogen-containing high dielectric constant insulating film with a structure in which nitrogen is introduced into a metal oxide or a metal silicate, the nitrogen concentration in the nitrogen-containing high dielectric constant insulating film has a distribution in the direction of the film thickness, and the position where the nitrogen concentration is maximum in the direction of the film thickness is present in a region away from the silicon substrate. A method for manufacturing a semiconductor device comprising a step of introducing nitrogen into a high dielectric constant insulating film of a metal oxide or a metal silicate by exposure to a nitrogen-containing plasma is also disclosed. As a result, the thermal stability of the high dielectric constant gate insulating film is improved, and the dopant penetration is suppressed, thereby preventing the electric characteristics of the interface with the silicon substrate from degrading.

Description

Description Semiconductor device and method for manufacturing the same

The present invention relates to a semiconductor device having a high dielectric constant thin film and a method for manufacturing the same, and more particularly to a semiconductor device having a metal oxide semiconductor field effect transistor (MOSFET). This technology is related to high performance and low power consumption of fl 吴. Background art

Silicon oxide film has process stability and excellent insulation properties, and is used as a gate insulating film material for MOS FETs. The gate insulating film is becoming thinner with the recent miniaturization of devices. For devices with a gate length of 100 nm or less, the thickness of the silicon oxide film, which is the gate insulating film, is 1.5 It is necessary to be smaller than nm. However, when such an extremely thin insulating film is used, the tunnel current with the insulating layer inserted when a gate bias is applied becomes a value that cannot be ignored with respect to the source Z drain current. This is a major issue in electrification.

Another problem with thinner gate dielectrics is the phenomenon of dopant diffusion from the gate electrode (polysilicon electrode). The gate electrode that is usually used in MOS FET is made by doping polysilicon deposited on a gate insulating film at a high concentration to have metallic properties. If it is thin, the problem that the dopant from the gate electrode penetrates through the insulating film layer and diffuses toward the silicon substrate becomes a problem.

Technology development is underway to solve the problems of increased leakage current and dopant penetration associated with the thinner gate insulating film. One of them is the silicon oxide film The addition of nitrogen increases the dielectric constant compared to pure silicon oxide, and reduces the effective (electrical) gate insulation layer thickness without reducing the physical thickness. It is a method to reduce. In addition, it has been confirmed that the addition of nitrogen suppresses the diffusion of dopants in the insulating film, and the addition of nitrogen to the gate insulating film has attracted attention as a promising technology for solving the above two problems. . However, there is a limit to increasing the dielectric constant by adding nitrogen to the silicon oxide film, and the mobility and reliability of the transistor deteriorate due to interface defects caused by nitrogen and the generation of fixed charges in the film. Is pointed out as a problem.

Therefore, as a material for the next-generation gate insulating film that replaces the silicon oxide film, the search for a material that has a higher dielectric constant than silicon oxynitride film / silicon nitride film and has an effect of preventing dopant diffusion has been promoted. ing. The first material having a high dielectric _{_{constant, AI 2 0 3, Z r}} O 2 and H f O _2, and Y ₂ 0 ₃ rare earth element oxides such as, also Rantanoido rare earth elements such as the L a ₂ 0 a These oxides, as well as these silicate thin films, are being studied as candidate materials.

The rationale is that the use of such a high dielectric constant film can prevent tunnel current while maintaining the gate insulating film capacitance in accordance with the scaling rule even when the gate length is reduced.

Regardless of the type of the gate insulating film, assuming that the gate insulating film material is a silicon oxide film, the thickness of the insulating layer obtained by calculating backward from the gate capacitance is called a silicon oxide film equivalent thickness. That is, assuming that the relative permittivity of the insulating film and the silicon oxide film is ε h and S o, respectively, and the thickness of the insulating film is dh, the equivalent silicon oxide film thickness de is de = dh (ε o / ε h) It becomes. It is shown that if a material having a dielectric constant ε h larger than ε o is used, a thick insulating film can be equivalent to a thin silicon oxide film. Since the relative dielectric constant ε ο of a silicon oxide film is about 3.9, for example, if a high dielectric film with ε h = 39 is used, even if the thickness is 15 nm, the equivalent silicon oxide film thickness is 1.5 nm. Therefore, the tunnel current can be drastically reduced.

As mentioned above, in the development of next-generation MOSFETs, 髙 It has been studied to adopt として the above-mentioned metal oxide thin film ゃ silicide thin film as the dielectric constant thin film. However, the following problems have been pointed out for these high dielectric constant thin films.

First, there is a problem of thermal stability of the high dielectric constant gate insulating film. In other words, it is reported that the high-k gate material is crystallized or an interfacial reaction with a silicon substrate proceeds in a heat treatment step for activating the dopant implanted in the gate electrode. When crystallization of the high dielectric constant film occurs, boundaries between crystal grains (crystal grain boundaries) are generated, and the insulation properties at these grain boundaries are degraded, and the in-plane thickness of the film due to the crystallization is reduced. Uniformity occurs. As a means of solving this crystallization problem, it is effective to select a high dielectric constant material having high thermal stability and to add nitrogen to the metal oxide / silicide film. On the other hand, oxygen in the gas phase easily diffuses into the high dielectric constant film, so that there is a problem that a reaction layer is formed at the interface with the silicon substrate during film formation and post-heat treatment.

To address this problem, a structure in which a very thin (usually about 0.5 nm to 1 nm) silicon oxide film is inserted at the interface between the high dielectric constant thin film and the silicon substrate has been studied. In recent years, it has been reported that a silicon oxynitride film / silicon nitride film is effective as the above-mentioned interface insertion layer.

As a second problem, it is known that, similarly to the silicon oxide film, the device characteristics of the high dielectric constant gate insulating film are deteriorated due to the penetration of the dopant. Although this problem is different depending on the type of insulating film material, the diffusion rate of the dopant in the film is high in the high-k gate insulating film despite the fact that the physical film thickness can be made larger than the silicon oxide film. This is a fatal problem when using a polysilicon gate electrode or a polysilicon germanium electrode. However, in recent research report, it can be suppressed dopant diffusion by adding nitrogen to A l ₂ 0 ₃ and Z r O ₂ have been reported.

The third problem is pointed out as follows: (1) Deterioration of the electrical characteristics at the interface between the dielectric constant thin film and the silicon substrate. In髙誘conductivity thin film interface compared to a conventional silicon oxide film interface high interfacial defect density, there is normally 1 0 "Z cm ² or more defects. MOSFET These interface defects (Oh Rui Makuchu defects) Mobility of several minutes compared to silicon oxide film The problem is that the threshold of transistor operation fluctuates due to degradation and fixed charges in the film and at the interface. As a remedy for these problems, it is effective to insert a silicon oxide film at the high dielectric constant thin film interface as in the remedy for the first problem. However, when the interfacial silicon oxide layer is thick, the equivalent oxide thickness of the entire gate insulating film increases. On the other hand, if the interfacial oxide layer is thin, the interfacial thermal stability and the effect of preventing dopant penetration are insufficient. Furthermore, a structure in which an ultra-thin silicon oxynitride / silicon nitride film is inserted at the interface between the high-dielectric-constant thin film and the silicon substrate is effective for improving interfacial thermal stability and suppressing dopant penetration, but deteriorates electrical characteristics. This is due to the introduction of new interface defects caused by nitrogen, which causes mobility and reliability degradation compared to the conventional silicon-silicon oxide interface.

As described above, introduction of nitrogen into the high dielectric constant gate insulating film is effective for solving the first and second problems, but nitrogen present at the interface with the silicon substrate has an adverse effect. When introducing nitrogen into the silicon oxide film, nitrogen can be introduced into the film by heat-treating the sample in a gas atmosphere containing nitrogen such as NH ₃ or NO gas. A large amount of nitrogen is biased at the interface of, causing the mobility and reliability degradation shown in the third problem. Nitrogen can also be introduced into a high-dielectric-constant insulating film by annealing in a gas atmosphere containing nitrogen, but also in this case, there is a concern about the problem of nitrogen segregation at the silicon substrate interface. I have.

As a new method for introducing nitrogen into a high dielectric constant thin film, a method of oxidizing a metal nitride film has been proposed (Koyama et al., Tech.Dig. IEDM 201, p459.) . Depositing a Z r N fl trillions by the specific sputtering surface of the silicon substrate, to which performs addition of nitrogen to the Z r O ₂ in at 5 0 0 ° C is subjected to oxidation treatment, conventional Z r O Excellent thermal stability compared to _two films. However, in this method, a SiON layer containing a high concentration of nitrogen is formed at the interface with the silicon substrate during the deposition of ZrN and during the oxidation treatment, and it is not possible to solve the third problem described above. Absent. Disclosure of the invention SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor device having a gate insulating film structure capable of simultaneously realizing the above-described measures for thermal stability, dopant penetration suppression, and improvement of interfacial electrical characteristics for device application of a dielectric constant gate insulating film. And a method for producing the same.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a conceptual diagram showing one embodiment of a semiconductor device of the present invention, and FIG. 2 is a flowchart showing one embodiment of a method of manufacturing a semiconductor device of the present invention.

FIG. 3 is a conceptual diagram showing another embodiment of the semiconductor device of the present invention. Furthermore, FIG. 4 is a graph showing the AI ₂ 0 ₃ film and a nitrogen inlet membrane nitrogen profiles measurements when performing in (secondary ion mass analysis) by nitrogen plasma exposure.

FIG. 5 is a graph showing the evaluation of the bonding state of the hafnium silicate surface subjected to the plasma nitriding treatment by X-ray photoelectron spectroscopy.

FIG. 6 is a flowchart showing another embodiment of the method of manufacturing a semiconductor device of the present invention (a method of manufacturing a gate insulating film structure by oxidizing a laminated structure having a metal nitride layer). FIG. 4 is a flowchart showing another embodiment of the method of manufacturing a semiconductor device of the present invention (a method of manufacturing a gate insulating film structure by oxidizing a stacked structure having a silicon nitride film).

Hereinafter, the symbols used in the drawings will be described.

Reference numeral 101 denotes a silicon substrate, reference numeral 102 denotes a silicon oxide film (interface oxide film layer), reference numeral 103 denotes a nitrogen-containing high dielectric constant insulating film, and reference numeral 104 denotes a gate electrode. Reference numeral 201 denotes a silicon substrate, reference numeral 202 denotes a hydrogen-terminated surface, reference numeral 203 denotes a silicon oxide film, reference numeral 204 denotes a metal layer, and reference numeral 205 denotes a metal layer. , A nitrogen-containing layer, reference numeral 206 denotes a nitrogen-containing dielectric constant insulating film, reference numeral 301 denotes a silicon substrate, reference numeral 302 denotes a silicon oxide film, and reference numeral 303 denotes a nitrogen-containing film. High dielectric constant insulating film, reference numeral 304 denotes a gate electrode, reference numeral 601 denotes a silicon substrate, reference numeral 602 denotes a hydrogen-terminated surface, reference numeral 603 denotes a silicon oxide film. Reference numeral 604 denotes a metal Zr deposited layer, reference numeral 605 denotes a ZrN deposited layer, reference numeral 606 denotes a nitrogen-containing high dielectric constant insulating film, reference numeral 701 denotes a silicon substrate, Reference numeral 702 indicates a hydrogen-terminated surface, reference numeral 703 indicates a silicon oxide film. Reference numeral 704 denotes an HfSi deposited layer, reference numeral 705 denotes a silicon nitride film, and reference numeral 706 denotes a nitrogen-containing high dielectric constant insulating film (nitrogen-containing Hf silicon layer). Is shown. BEST MODE FOR CARRYING OUT THE INVENTION

As a first embodiment of the present invention, in a semiconductor device having a gate insulating film and a gate electrode in this order on a silicon substrate,

The gate insulating film has a nitrogen-containing high dielectric constant insulating film having a structure in which nitrogen is introduced into a metal oxide or a metal silicate, and the nitrogen concentration in the nitrogen-containing high dielectric constant insulating film is increased in the thickness direction. Has a distribution,

A semiconductor device is provided in which a position where the nitrogen concentration in the nitrogen-containing high dielectric constant insulating film becomes maximum in the film thickness direction is located in a region away from the silicon substrate.

In this semiconductor device, it is preferable that the position where the nitrogen concentration in the nitrogen-containing high-dielectric-constant insulating film becomes maximum in the film thickness direction is in a region separated from the silicon substrate by 0.5 nm or more.

It is also preferable that the position where the nitrogen concentration in the nitrogen-containing high dielectric constant insulating film becomes maximum in the film thickness direction is localized on the gate electrode side of the nitrogen-containing high dielectric constant insulating film.

It is also preferable that the position where the nitrogen concentration in the nitrogen-containing high dielectric constant insulating film becomes maximum in the film thickness direction is localized at the center of the nitrogen-containing high dielectric constant insulating film.

It is also preferable that the nitrogen concentration at the interface between the gate insulating film and the silicon substrate is less than 3 atomic%.

As a second mode of the present invention, in a semiconductor device having a gate insulating film and a gate electrode in this order on a silicon substrate,

The gate insulating film has a nitrogen-containing high dielectric constant insulating film having a structure in which nitrogen is introduced into a metal silicate,

There is provided a semiconductor device in which nitrogen atoms in the nitrogen-containing high dielectric constant insulating film are selectively bonded to silicon atoms in metal silicate.

In this semiconductor device, selectively bonding with silicon atoms in the metal silicide It is preferable that the removed nitrogen atoms be present at positions away from the silicon substrate. In the above semiconductor device, the gate insulating film has a silicon oxide film formed in contact with the silicon substrate and the nitrogen-containing high dielectric constant insulating film formed in contact with the silicon oxide film. Is preferred.

According to a third aspect of the present invention, in a semiconductor device having a gate insulating film and a gate electrode on a silicon substrate in this order,

The composition of the nitrogen-containing high-dielectric-constant insulating film continuously changes in the film thickness direction, and silicon is present at an intermediate portion between the interface between the silicon-substrate-side interface and the gate electrode-side interface of the nitrogen-containing high-dielectric-constant insulating film. The concentration has a minimum,

There is provided a semiconductor device characterized in that nitrogen is introduced only between a position where the silicon concentration has a minimum value and the gate electrode side interface.

As a fourth mode of the present invention, in a semiconductor device having a gate insulating film and a gate electrode in this order on a silicon substrate,

The gate insulating film has a stacked structure including a first silicon oxide film, a metal oxide film or a metal silicate film, and a second silicon oxide film in order from the silicon substrate side, and only the second silicon oxide film is formed. There is provided a semiconductor device having a structure in which nitrogen is introduced into silicon oxide.

In the above semiconductor device, it is preferable that the silicon substrate and the gate insulating film are in contact, the gate insulating film is in contact with the gate electrode, and the gate electrode is a polysilicon or polysilicon germanium conductive film.

In the above-described semiconductor device, the gate insulating film may be composed of Zr, Hf, Ta, Al, Ti, Nb, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd , Tb, Dy, Ho, Er, Tm, Yb, and Lu.

According to the present invention, a gate insulating film and a gate electrode are formed on a silicon substrate in this order. In a method of manufacturing a semiconductor device having

The semiconductor device according to the first, second, or third aspect, wherein a step of introducing the nitrogen by irradiating a nitrogen-containing plasma to a high dielectric constant insulating film made of a metal oxide or a metal silicate is included. A method for manufacturing a semiconductor device is provided.

According to the present invention, in a method for manufacturing a semiconductor device having a gate insulating film and a gate electrode in this order on a silicon substrate,

The semiconductor device is the semiconductor device according to the fourth aspect,

A method for manufacturing a semiconductor device is provided, comprising a step of introducing the nitrogen by irradiating the stacked structure with a nitrogen-containing plasma.

The semiconductor device is the semiconductor device according to the second aspect,

A step of selectively forming only a bond between silicon and nitrogen in the metal silicide by irradiating the high dielectric constant thin film composed of the metal silicide with nitrogen-containing plasma, and introducing the nitrogen. A method for manufacturing a semiconductor device is provided.

The semiconductor device according to the first, second, or third aspect, wherein a stacked structure including a metal layer and a nitrogen-containing layer containing nitrogen is formed on a silicon substrate and then subjected to oxidation treatment. There is provided a method for manufacturing a semiconductor device, comprising a step of forming a gate insulating film.

In this manufacturing method, it is preferable that the nitrogen-containing layer is a silicon oxynitride film or a silicon nitride film.

In this manufacturing method, it is also preferable that the nitrogen-containing layer is a metal nitride film.

In addition, in this manufacturing method, the silicon substrate surface has a thickness of less than 1 nm. It is also preferable to form the laminated structure after forming the oxide film.

According to the present invention, in a semiconductor device having a gate insulating film and a gate electrode in this order on a silicon substrate,

The gate insulating film contains nitrogen and a metal oxide or metal silicate,

The nitrogen concentration in the gate insulating film has a distribution in the thickness direction,

There is also provided a semiconductor device, wherein a position where the nitrogen concentration in the gate insulating film becomes maximum in the film thickness direction is located in a region away from the silicon substrate.

In the present invention, the position where the nitrogen concentration in the high dielectric constant gate insulating film becomes maximum is preferably separated from the silicon substrate interface by 0.5 nm or more, and the nitrogen at the interface between the high dielectric constant gate insulating film and the silicon substrate is A gate insulating film structure with a concentration preferably reduced to less than 3% is proposed. As a manufacturing method for realizing the gate insulating film structure, a step of selectively nitriding a region other than the vicinity of the silicon substrate by exposing to a plasma containing nitrogen, or a lamination of a metal layer and a nitrogen-containing layer on a silicon substrate By adopting the step of performing the oxidation treatment after forming the structure, the distribution of nitrogen in the gate insulating film can be controlled.

The high dielectric constant means that the dielectric constant is higher than that of the silicon nitride film. More specifically, the relative dielectric constant of the high dielectric constant gate insulating film is preferably 8 or more, more preferably 10 or more, from the viewpoint that the equivalent silicon oxide film thickness can be reduced. However, when alumina is used as the metal oxide, the number may be 7 or more.

FIG. 1 shows a semiconductor device having a typical high dielectric constant gate insulating film structure proposed in the present invention. Here, nitrogen is localized in the upper layer of the high-dielectric-constant thin film made of metal oxide or metal silicide to form a nitrogen-containing high-dielectric-constant insulating film 103. A gate insulating film structure composed of a nitrogen-containing high dielectric constant insulating film 103 and a silicon oxide film 102 formed by inserting an interface oxide film layer (silicon oxide film 102) will be described as an example.

First, the effects provided by the gate insulating film structure shown in FIG. 1 will be described below. By adding nitrogen to the metal oxide or metal silicate, the thermal stability of the high dielectric constant thin film can be improved. The thermal stability of the interface between the dielectric constant thin film and the silicon substrate Can be improved by inserting an extremely thin silicon oxide film 102 at the interface between the high dielectric constant thin film and the substrate. On the other hand, since the high concentration of nitrogen is localized above the high dielectric constant thin film, it is possible to suppress the penetration of the dopant from the gate electrode. Furthermore, the electrical characteristics of the interface between the silicon substrate and the silicon substrate are based on the fact that the high dielectric constant thin film is not in direct contact with the silicon substrate, but rather through the ultra-thin silicon oxide film. It is possible to suppress mobility and reliability deterioration.

Various methods can be considered as a method for manufacturing the gate insulating film in the present invention. For example, a selective nitriding method of a high-dielectric-constant thin film by applying nitrogen-containing plasma irradiation and lamination of a metal layer and a nitrogen-containing layer are described below. Nitrogen introduction and profile control through the oxidation process of the structure are effective.

The first method of applying plasma irradiation is to form a gate insulating film (with no nitrogen introduced) containing a high dielectric constant insulating film on a silicon substrate, and irradiate it with active nitrogen generated by plasma. . For example, a high dielectric constant insulating film made of a metal oxide or a metal silicate can be formed, and the surface of the high dielectric constant insulating film can be irradiated with nitrogen-containing plasma. By adjusting the plasma generation conditions, it is possible to supply active nitrogen that is extremely reactive with the elements that make up the gate insulating film or high-dielectric-constant insulating film. The diffusion of nitrogen into the gate insulating film can be suppressed to prevent nitrogen from reaching the silicon substrate, and only the film surface (or a region other than the interface with the silicon substrate) can be selectively selected. It becomes possible to nitride. In other words, it is possible to localize the nitrogen profile in a region (film surface side) distant from the silicon substrate interface.

In the second manufacturing method, the nitrogen concentration distribution in the film can be controlled by the oxidation treatment of the laminated structure shown in the flowchart of FIG. For example, after an ultra-thin silicon oxide film 203 is formed on the surface of the silicon substrate 201 (hydrogen-terminated surface 202) (FIG. 2B), a metal layer is formed on the surface of the oxide film. A metal layer 204 is deposited (FIG. (C)). Subsequently, as a nitrogen-containing layer 205, which is a layer containing nitrogen, a metal nitride layer is deposited on the metal layer to form a laminated structure ((d) in the same figure), and heat treatment is performed in an oxygen atmosphere. By applying metal While oxidizing the layer, the nitrogen concentration in the high dielectric constant insulating film can be localized near the surface layer. Thus, a nitrogen-containing high dielectric constant insulating film 206 having a nitrogen concentration distribution as shown in FIG. 2 (e) can be obtained, and the nitrogen-containing high dielectric constant insulating film 206 and the silicon oxide film are obtained. A gate insulating film made of 203 can be formed. As the nitrogen-containing layer, a nitride film of a metal element constituting a metal oxide, a silicon nitride film (oxynitride film), or the like is effective. An effective technique for depositing a metal nitride is a metal nitride target or a reactive sputtering method using a metal target. The thickness of the nitrogen-containing layer is preferably 1 nm or more from the viewpoint of suppressing the diffusion of the dopant, etc., since even if a large amount of nitrogen is contained, the effect of nitrogen inclusion does not improve in proportion thereto. It is preferably not more than nm.

The oxidation treatment is appropriately determined depending on the material to be used. For example, the oxidation treatment can be performed at 500 to 900 °.

After the gate insulating film is formed on the silicon substrate in this manner, a gate electrode is provided thereon by a known method, whereby the semiconductor device of the present invention can be obtained. In the structure of the semiconductor device of the present invention, by adding nitrogen to the gate insulating film having a high dielectric constant thin film, the thermal stability is improved and the dopant penetration phenomenon from the gate electrode side is suppressed, and at the same time, the gate insulating film is formed. The problem of mobility degradation and reliability degradation is solved by localizing the position of nitrogen in the film away from the silicon substrate interface and on the film surface or central portion.

The nitrogen distribution in the gate insulating film that achieves the above effects is not limited to the profiles shown in the conceptual diagram of FIG. 1, but the effects can be obtained for various profiles shown in FIG. Fig. 3 (a) shows the case where nitrogen is distributed almost uniformly in a part of the high dielectric constant insulating film 303, which was inserted at the interface between the high dielectric constant insulating film and the silicon substrate 301. This is the case where the nitrogen concentration sharply drops at the interface between the silicon oxide film 302 and the high dielectric constant insulating film, and no nitrogen exists in the silicon oxide film 302 inserted into the interface. Fig. 3 (b) shows the case where the maximum value of the nitrogen concentration is located at the center of the high-k insulating film (nitrogen is localized at the center). With The nitrogen concentration drops sharply toward the interface, and there is no nitrogen at the interface with the silicon substrate. Also, in Fig. 3 (c), 髙 although the profile shape is such that nitrogen is localized on the surface side (gate electrode side) in the dielectric constant insulating film, で due to nitrogen diffusion in the dielectric constant insulating film, etc. This is the case where some nitrogen segregates at the interface between the high dielectric constant insulating film and the silicon oxide film. In such a case, if the distance from the interface between the silicon oxide film and the silicon substrate to the region where nitrogen is localized is less than 1 nm, depending on the situation, it may move due to the effects of nitrogen-induced fixed charges at the interface. Although it is disadvantageous in that it may cause deterioration in reliability and reliability, the region where nitrogen is localized (the maximum value of the nitrogen concentration in the nitrogen-containing high dielectric constant insulating film in the thickness direction) is preferably 0% from the silicon substrate. If the distance is 5 nm or more, more preferably 1 nm or more, and the nitrogen concentration near the silicon substrate interface is sufficiently low, the structures shown in FIGS. 1 and 3 (a) and (b) Of course, an excellent semiconductor device can be obtained even with the structure shown in FIG. 3 (c). At this time, the allowable nitrogen concentration at the silicon substrate interface is related to the allowable value of device mobility degradation and reliability degradation (device design), but from the viewpoint of interface electrical characteristics, the allowable nitrogen concentration at the silicon substrate interface of the gate insulating film. The nitrogen concentration is preferably less than 3 atomic%, and it is more preferable that nitrogen does not exist at the substrate interface. Further, the maximum nitrogen concentration in the gate insulating film is desirably 1 atomic% or more in order to obtain the thermal stability and the effect of suppressing dopant penetration. From the viewpoint of the insulating properties and reliability of the gate insulating film, it is desirable that the maximum amount of the nitrogen concentration in the film is less than 20 atomic%. However, the nitrogen concentration range is deeply involved in the design of the device characteristics, and is not limited to the above range.

First, a silicon oxide film is formed on the surface of a silicon substrate, and then a stacked structure including a metal layer and a nitrogen-containing layer is formed thereon. The thickness of the oxide film is preferably less than 1 nm from the viewpoint of reducing the equivalent silicon oxide film thickness to the physical thickness of the gate insulating film. Further, from the viewpoint of interfacial electric characteristics, the thickness is preferably 0.5 nm or more.

The thickness of the nitrogen-containing high dielectric constant gate insulating film varies depending on the case. For example, the physical thickness of the gate insulating film is 1.5 n from the viewpoint of preventing a sudden increase in the leak current at present. m or more, and the present invention can be suitably applied to such a gate insulating film. If the maximum value of the nitrogen concentration in the film thickness direction is more than 0.5 nm away from the silicon substrate, a film thickness exceeding 0.5 nm is naturally required.

As the high dielectric constant insulating film material for introducing nitrogen, the oxidation of _{Z r 0 2, H f 0} 2, T a 2 0 5, AI 2 0 3, T i O 2, N b 2 0 5 or a rare earth element _{_{_{S c 2 0 Y 2 0 3}}} , also La 203 is an oxide of Rantanoido based element, Ce02, P r 203, N d 2 03, Sm203, E u 203 is _{intended, G d 2 O 3 S T} b 203 , D y 203, Ηο 2 θ 3, E r 203, Tm 2 0 3, Y b 2 0 3, L u 2 0 3, further there is a silicate one Bok material obtained by adding a divorced these metal oxides .

As shown in FIGS. 1 to 3 described above, in addition to the structure in which an ultra-thin silicon oxide film is inserted at the interface between the high dielectric constant insulating film and the silicon substrate from the viewpoint of improving the interfacial electrical characteristics, In order to improve the interfacial electrical characteristics with the gate electrode (for example, polysilicon or polysilicon germanium electrode) provided on the gate insulating film, the ultra-thin silicon oxide film is also stacked on the high dielectric constant insulating film. It is effective to selectively nitride only the silicon oxide film layer on the surface side (gate electrode side) (or a region away from the silicon substrate interface). The gate insulating film in this case has, for example, a stacked structure including a first silicon oxide film, a film made of a metal oxide or a metal silicate, and a second silicon oxide film from the silicon substrate side. Nitrogen is introduced only into the first silicon oxide film, and nitrogen is not introduced into the first silicon oxide film and the film made of metal oxide or metal silicate.

The thickness of the first and second silicon oxide films is preferably 0.5 nm or more from the viewpoint of the effect of improving interfacial electrical characteristics, and the equivalent silicon oxide film thickness is smaller than the physical thickness of the gate insulating film. The thickness is preferably 1 nm or less from the viewpoint of the performance. Further, the thickness of the film made of the metal oxide or metal silicate is preferably 2 nm or more from the viewpoint of suppressing the tunnel current, and 5 nm or less from the viewpoint of easiness of manufacture and balance of the shape of the semiconductor device. preferable.

In addition, the above-mentioned silicon oxide film High dielectric constant insulating film Even if it is not a laminated structure having an interface, it is a structure in which the composition in the thickness direction of the metal silicide thin film is modulated, as proposed in Japanese Patent Application No. 2001-252522. As for the structure in which the silicon composition is increased in the upper layer and the lower layer of the gate insulating film, a structure in which only the region having a high silicon concentration on the surface side is selectively nitrided is also effective. In this gate insulating film structure, the gate insulating film has a nitrogen-containing 髙 dielectric constant insulating film having a structure in which nitrogen is introduced into a metal silicate, and the composition of the nitrogen-containing 率 dielectric constant insulating film is in accordance with the film thickness. The silicon concentration has a minimum value at an intermediate portion between the silicon substrate-side interface and the gate electrode side interface of the nitrogen-containing high dielectric constant insulating film, and the silicon concentration has a minimum value. Nitrogen is introduced only between the position and the interface on the gate electrode side, and no nitrogen is introduced between the position where the silicon concentration has the minimum value and the interface on the silicon substrate side. In such a structure, the concentration of the metal element in the metal silicate increases in the middle portion, and the silicon composition increases in the upper and lower layers of the film, so that the gate insulating film and the silicon substrate (lower interface) and At the boundary with the gate electrode (upper interface), it is possible to form a structure close to the SiO ₂ / Si interface, and the interface electrical characteristics can be improved. It is also feared that the silicate temperature of a high-concentration silicate material is relatively low. However, by forming a structure in which this high-concentration metal region is sandwiched by a high-concentration silicon high-concentration region, thermal conductivity is increased. Stability can be improved.

As an example of the above structure, a nitrogen-containing high-permittivity insulating film in which the composition of the metal silicate changes in the film thickness direction is divided into a first region, an intermediate region, and a second region from the silicon substrate side. (The first region is in contact with the silicon substrate and the second region is in contact with the gate electrode), the silicon concentration in the metal silicide decreases continuously from the silicon substrate side interface of the first region, In a mode in which the minimum value is reached in the intermediate region, the value then increases, and continuously increases to the gate electrode side interface in the second region. In the first and second regions, silicon metal is used. The element ratio is higher than the average value of the entire gate insulating film, the silicon metal element ratio is lower than the average value of the entire gate insulating film in the intermediate region, and nitrogen is introduced only in the second region. . In such a case, the thickness of the first and second regions is preferably 0.5 nm or more from the viewpoint of the effect of improving interfacial electrical characteristics. The thickness is preferably 1 nm or less from the viewpoint of reducing the equivalent silicon oxide film thickness to the physical thickness of the insulating film. The thickness of the intermediate region is preferably 2 nm or more from the viewpoint of suppressing tunnel current, and is preferably 5 nm or less from the viewpoint of easiness of manufacturing and the balance of the shape of the semiconductor device.

In addition, when nitrogen is introduced into the high dielectric constant insulating film or silicon oxide film, the metal element constituting the metal oxide or metal silicate layer or silicon in the silicate, or the upper layer of the high dielectric constant film or Several bonding modes (metal-nitrogen, silicon-nitrogen, or oxygen-nitrogen bonds) between the silicon-oxygen and nitrogen atoms that make up the silicon oxide film inserted in the lower layer can be considered. Of these bonds, a substance composed of a bond between a metal atom and a nitrogen atom often has relatively low insulating properties, so that when introducing nitrogen into a film, a large amount of a metal-nitrogen bond is formed. It is preferable to have a structure in which silicon atoms are selectively nitrided while suppressing silicon. However, regarding AI, aluminum nitride (AIN) is a material with excellent insulating properties, and this point does not need to be considered when nitriding Al ₂ O ₃ materials. In a structure in which silicon atoms are selectively nitrided, there are more silicon-nitrogen bonds than metal-nitrogen bonds.

When a gate insulating film (without introducing nitrogen) containing a high dielectric constant insulating film is formed on a silicon substrate and irradiated with a nitrogen-containing plasma, a high dielectric constant thin film made of metal oxide and silicon are used. In the case of performing a plasma nitridation process on a laminated structure with an oxide film or a metal silicate thin film, it is possible to selectively nitride only silicon atoms in the film (particularly on the film surface side) by adjusting the plasma irradiation conditions. . Example

Examples of a semiconductor device having a high dielectric constant gate insulating film structure and a method of manufacturing the same according to the present invention will be described below.

(Example 1)

In the first embodiment of the present invention, an AI ₂ O ₃ film formed by an atomic layer deposition method (Atomic Layer Chemical I Vapor Deposition: ALD) is used. The result of introducing nitrogen by irradiation of nitrogen radicals therein is shown.

Field regions of the MOS FET formed in advance on a silicon wafer, this area in the underlying oxide film (interface oxide layer) The film thickness 0. 6 nm of silicon oxide film formed was _c present on the wafer AI (CH ₃₎ ₃ and H ₂ 0 source gas One by ALD method by alternately supplying after the deposition of the AI ₂ 0 ₃ film having a thickness of 4 nm, was irradiated with nitrogen radicals to the surface. Radical irradiation was performed by a vacuum apparatus equipped with an ECR (Electron Cyclotron Resonance) radical source as a plasma source. Radical source is located in the wafer just above 20 cm, the _c nitrogen radical irradiation conditions were a substrate temperature of 300~ 70 0 ° C, pressure 0. 3 ~ 0. 9 P a , the nitriding treatment for 30 minutes as a power 1 50 W FIG. 4 is a typical radical irradiation condition results nitrogen concentration of AI ₂ 0 ₃ film obtained by nitriding prepared was evaluated by secondary ion mass spectrometry. From these results, when the substrate temperature is high and the nitrogen gas pressure is low (700 ° C, 0.3 Pa), nitrogen is distributed over the entire film and high concentration nitrogen is introduced to the interface. When the temperature was lowered and the nitrogen gas pressure was raised (300 ° C, 0.9 Pa), the nitrogen concentration in the film decreased, and a profile in which nitrogen was localized on the surface side was obtained. You can see that it is done. Therefore, the amount of nitrogen introduced can be controlled by the substrate temperature, and the nitrogen concentration in the film can be localized on the film surface side by optimizing the nitrogen gas partial pressure (in the above case, increasing the pressure). It is.

As a result of fabricating MOS FETs using high-concentration doped polysilicon using these nitrided high dielectric constant gate insulating films as gate electrodes, thermal stability was improved for all nitrogen-introduced samples. In addition, the effect of suppressing penetration of the dopant was confirmed. As a result of further performing mobility evaluation transistors, transistors nitrogen concentration at the interface had a high gate insulating film (nitride Conditions: 700 ° C, 0. 3 P a) to AI ₂ 0 ₃ film surface as compared with The mobility is approximately 20 for a transistor having a gate insulating film structure in which nitrogen is localized (nitriding conditions: 300 ° C, 0.9 Pa). Was growing. (Example 2)

In the second embodiment, nitriding treatment was performed by irradiating hafnium siligate (HfSIO) with nitrogen plasma. A MOSFET field region was formed on a silicon wafer in advance, and a 0.6-nm-thick silicon oxide film was formed in this region as a base oxide film (interface oxide layer). A 3 nm-thick silicate film containing 10 atomic% of Hf formed thereon was irradiated with active nitrogen generated from nitrogen gas using an ECR plasma source. The irradiation conditions were a substrate temperature of 300 ° C., a nitrogen partial pressure of 6.7 Pa, and a power supply of 60 for 1 minute. As a result, a silicide film containing 10 <½ of nitrogen in atomic% was obtained.

As a result of secondary ion mass spectrometry similar to that described above, nitrogen was distributed in the film with a peak at 0.5 nm from the film surface side, and the nitrogen content gradually decreased in the depth direction and decreased. Nitrogen was not detected at the interface with the recon substrate. FIG. 5 shows the X-ray photoelectron spectrum (Si 2 p core level spectrum) obtained from the H f silicate film before and after the plasma irradiation in this example. In this measurement result, the peak energy of 102.5 eV caused by the silicide is shifted to the lower binding energy side by nitriding. This indicates that S i -N bonds were formed in the film. On the other hand, there was no change in the Hf4f spectrum, and it appeared at the position of the normal hafnium silicate after nitriding, confirming that no Hf-N bond was formed in the film. . These results indicate that the silicon atoms on the surface side in the silicon silicate were selectively nitrided by the above-described nitriding treatment. As a result of fabricating a MOSFET having this hafnium silicide film as a gate insulating film, an untreated (no nitrogen introduced) hafnium sili- gate was obtained because the formation of Hf-N bonds was suppressed in a selective nitridation process. No increase in leakage current was observed as compared with the transistor that was fabricated. Thermal stability was improved by the nitrogen introduction effect (the crystallization temperature was improved by 100 ° C or more), and the mobility and reliability did not deteriorate due to the nitrogen introduction. Further, the effect of preventing dopant penetration from the polysilicon gate was confirmed. In the present embodiment, the Si—O bond in the silicate film is selectively replaced with nitrogen, so that nitrogen can be contained in the silicate film without an increase in leak current. As a result, the relative dielectric constant increases (the average dielectric constant of the silicide film increases from 10 to 12). In the same manner, when a zirconium silicide or a lanthanum silicide was nitrided instead of a hafnium silicide, the same effect was obtained. Obtained.

(Example 3)

In a third embodiment of the present invention show in accordance with the flow diagram of an example in which the nitrogen added to the Z r O ₂ in the high dielectric constant萍膜inserting the silicon oxide film extremely thin silicon substrate interface Figure 6 _c After cleaning the silicon wafer 601, the chemical oxide film formed on the substrate surface was separated by hydrofluoric acid solution treatment, and the silicon surface was terminated with hydrogen atoms ((a) in the same figure). This wafer was oxidized at 700 ° C. in a reduced-pressure oxygen atmosphere of 5 Torr (670 Pa) to form a 0.6 nm-thick silicon oxide film 603 (FIG. 2B). The deposition of the metal layer and the nitrogen-containing layer on the surface of the oxide film was performed using a sputtering system having a plurality of targets. For sputter deposition, a low-damage deposition method employing ECR discharge was adopted.Argon gas was used as the sputtering gas, gas pressure was 5 × 10-4 Torr (0.067 Pa), and high-frequency output was 100 W. . After depositing a metal Zr layer 604 having a thickness of 2 nm on the silicon oxide film 603 at a substrate temperature of room temperature (FIG. (C)), the target is replaced and the substrate temperature is reduced to room temperature. 1. deposited Z r N layer 605 O nm was formed Z r NZZ r / S i O 2 laminated structure (Fig. (d)). The oxidation treatment of this sample was performed at 500 ° C. in a reduced-pressure oxygen atmosphere of 1 Torr (130 Pa). I oxidation connexion metal layer (metal nitride layer) is converted to _{Z r O 2 (Z r ON} ) layer, a high dielectric constant insulating film (Z r ON high dielectric constant film) containing nitrogen 606 was obtained . The composition distribution in the film thickness direction was evaluated by secondary ion mass spectrometry. As a result, it was localized at a position of 0.6 nm from the film surface, and the nitrogen concentration was the maximum value of 10% in atomic%. Further, at the interface between the silicon substrate was confirmed to have been retained S ί ο ₂ composition.

Thereafter, a polysilicon electrode was formed on the gate insulating film having the silicon oxide film 603 and the high-dielectric-constant insulating film 606 manufactured by the above-described manufacturing method, thereby manufacturing a MOSF. When the gate insulating film capacitance and current-voltage characteristics of this MOS F F device were evaluated, the equivalent silicon oxide film thickness was 1.4 nm, and the leakage current flowing through the gate insulating film was equivalent to the equivalent oxide film thickness. It was reduced by about three orders of magnitude compared to the silicon oxide film. In addition, the crystallization temperature of the gate insulating film layer is lower than that when nitrogen is not added. Improved by 50 ° C or more. Furthermore, no abnormalities in the transistor operating characteristics due to the penetration of the dopant were observed in the heat treatment at 1050 ° C, which is the dopant activation step.

(Example 4)

In the fourth embodiment, a ZrO 2 fl matrix with nitrogen localized on the surface side was prepared in the same procedure as in the third embodiment, and then a polysilicon germanium electrode was formed as a gate electrode. Compared with the third embodiment (polysilicon gate electrode), the effect of gate electrode depletion was reduced, and the on-current of the transistor was increased.

(Example 5)

In the fifth embodiment, nitrogen was added via a silicon nitride film to a Hf silicate high dielectric constant thin film having a silicon oxide film inserted at the silicon substrate interface (FIG. 7).

After cleaning the silicon wafer 701 and stripping the chemical oxide film in the same manner as in Example 3 (FIG. 7A), a silicon oxide film 703 having a thickness of 0.6 nm was formed (FIG. 7B). An amorphous ^! 51 layer 704 with a physical film thickness of 2 nm was formed on this surface by sputter deposition using an HfSi sintered body target (Fig. 3 (c)). The sputtering film formation conditions were the same as in Example 2. Then, a 0.5 nm thick silicon nitride film 705 was formed on the surface of the wafer by CVD (chemical vapor deposition) using SiH ₄ and NH ₃ as source gases (see FIG. )). The sample was oxidized at 700 ° C. in a reduced pressure oxygen atmosphere of 1 Torr (130 Pa) to form a nitrogen-introduced hafnium silicate (HfSiO) film 706, A nitrogen-containing high dielectric constant insulating film was used.

As a result of evaluating the composition distribution of this sample by secondary ion mass spectrometry, it was found that the interface reaction between the silicon oxide film and the Hf silicate gate, and the interface reaction between the Hf silicate layer and the silicon nitride film (silicon oxygen nitrogen film) on the surface side. Mixing occurs at the layer level, but the nitrogen concentration peak is 10% at atomic%, has a maximum value at 0.5 nm from the surface, and the Si02 composition is maintained at the interface with the silicon substrate Confirmed that. In this manner, a MOS FET formed by forming a gate insulating film having a silicon oxide film 703 and a hafnium silicate layer 706, and forming a gate electrode thereon. In this case, the equivalent silicon oxide film thickness was 1.6 nm, and the leakage current was about two orders of magnitude lower than that of a silicon oxide film with an equivalent oxide film thickness. Industrial applicability

By adopting a structure in which the nitrogen distribution in the gate insulating film structure composed of a metal oxide thin film or a silicide thin film to which nitrogen is added according to the present invention is separated from the silicon substrate interface, the thermal stability of the high dielectric constant thin film is improved. There has been provided a semiconductor device capable of simultaneously obtaining a plurality of effects such as improvement of the resistance, prevention of the penetration of dopant from the gate electrode, and prevention of deterioration of the electrical characteristics at the interface between the gate insulating film and the silicon substrate. Further, according to the present invention, there is provided a manufacturing method effective for manufacturing a semiconductor device having a gate insulating film structure having the above-mentioned high dielectric constant thin film.

Claims

The scope of the claims

1. In a semiconductor device having a gate insulating film and a gate electrode in this order on a silicon substrate,

The gate insulating film has a nitrogen-containing high dielectric constant insulating film having a structure in which nitrogen is introduced into a metal oxide or a metal silicate;

The nitrogen concentration in the nitrogen-containing dielectric insulating film has a distribution in the film thickness direction,

A semiconductor device, wherein the position where the nitrogen concentration in the nitrogen-containing high dielectric constant insulating film becomes maximum in the film thickness direction is located in a region away from the silicon substrate.

2. The semiconductor device according to claim 1, wherein the position where the nitrogen concentration in the nitrogen-containing high-dielectric-constant insulating film becomes maximum in the film thickness direction is in a region separated from the silicon substrate by 0.5 nm or more.

3. The semiconductor device according to claim 1, wherein the position where the nitrogen concentration in the nitrogen-containing high dielectric constant insulating film is maximum in the film thickness direction is localized on the gate electrode side of the nitrogen-containing high dielectric constant insulating film.

4. The semiconductor device according to claim 1, wherein a position where a nitrogen concentration in the nitrogen-containing high dielectric constant insulating film is maximum in a film thickness direction is localized in a central portion of the nitrogen-containing high dielectric constant insulating film.

5. The semiconductor device according to claim 1, wherein a nitrogen concentration at an interface of the gate insulating film on the silicon substrate side is less than 3 atomic%.

6. In a semiconductor device having a gate insulating film and a gate electrode in this order on a silicon substrate,

A semiconductor device in which nitrogen atoms in the nitrogen-containing high dielectric constant insulating film are selectively bonded to silicon atoms in a metal silicide.

7. The semiconductor device according to claim 6, wherein a nitrogen atom selectively bonded to a silicon atom in the metal silicide exists at a position distant from the silicon substrate.

8. The gate insulating film has a silicon oxide film formed in contact with the silicon substrate, and the nitrogen-containing high dielectric constant insulating film formed in contact with the silicon oxide film. The semiconductor device according to claim 1, wherein:

9. In a semiconductor device having a gate insulating film and a gate electrode in this order on a silicon substrate,

The composition of the nitrogen-containing high dielectric constant insulating film changes continuously in the film thickness direction, and the silicon concentration in the intermediate portion between the interface between the silicon substrate side and the gate electrode side of the nitrogen-containing high dielectric constant insulating film is reduced. Has a minimum value,

A semiconductor device characterized in that nitrogen is introduced only between a position where the silicon concentration has a minimum value and the gate electrode side interface.

10. In a semiconductor device having a gate insulating film and a gate electrode in this order on a silicon substrate,

The gate insulating film has a laminated structure including a first silicon oxide film, a metal oxide film or a metal silicate film, and a second silicon oxide film in order from the silicon substrate side,

A semiconductor device, characterized in that only the second silicon oxide film has a structure in which nitrogen is introduced into silicon oxide.

1 1. The silicon substrate is in contact with the gate insulating film, the gate insulating film is in contact with a gate electrode, and

The semiconductor device according to any one of claims 1 to 10, wherein the gate electrode is polysilicon or a polysilicon germanium conductive film.

1 2. The gate insulating film is composed of Zr, Hf, Ta, Al, Ti, Nb, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, The semiconductor device according to any one of claims 1 to 11, comprising at least one selected from the group consisting of Tb, Dy, Ho, Er, Tm, Yb, and Lu.

1 3. In a method of manufacturing a semiconductor device having a gate insulating film and a gate electrode on a silicon substrate in this order, The semiconductor device according to claim 1, wherein the nitrogen is introduced by irradiating a high-k insulating film made of metal oxide or metal silicide with nitrogen-containing plasma. A method for manufacturing a semiconductor device, comprising:

14. In a method for manufacturing a semiconductor device having a gate insulating film and a gate electrode in this order on a silicon substrate,

The semiconductor device according to claim 10, wherein:

A method for manufacturing a semiconductor device, comprising a step of introducing the nitrogen by irradiating the stacked structure with nitrogen-containing plasma.

15. In a method for manufacturing a semiconductor device having a gate insulating film and a gate electrode in this order on a silicon substrate,

The semiconductor device according to claim 6 or 7, wherein

A method of selectively forming only a bond between silicon and nitrogen in a metal silicate by irradiating a nitrogen-containing plasma to a 髙 dielectric constant thin film made of a metal silicide, and introducing the nitrogen. Semiconductor device manufacturing method.

16. In a method of manufacturing a semiconductor device having a gate insulating film and a gate electrode in this order on a silicon substrate,

The semiconductor device according to any one of claims 1 to 9, wherein the oxidation treatment is performed after forming a stacked structure including a metal layer and a nitrogen-containing layer containing nitrogen on the silicon substrate. A method for manufacturing a semiconductor device, comprising a step of forming a gate insulating film.

17. The method according to claim 16, wherein the nitrogen-containing layer is a silicon oxynitride film or a silicon nitride film.

18. The method according to claim 16, wherein the nitrogen-containing layer is a metal nitride film.

19. The method for manufacturing a semiconductor device according to any one of claims 16 to 18, wherein the stacked structure is formed after forming a silicon oxide film having a thickness of less than 1 nm on a silicon substrate surface.

20. In a semiconductor device having a gate insulating film and a gate electrode in this order on a silicon substrate,

The gate insulating film contains nitrogen and a metal oxide or a metal silicide,

A semiconductor device, wherein a position where the nitrogen concentration in the gate insulating film is maximum in a film thickness direction is located in a region away from the silicon substrate.